Are there any contracts that allow you to temporarily change another person into a creature, like a bird or dog?
No, there are not.
The 5th dot of Fang and Talon in core lets you change yourself. There is no basic metamagic that lets you change the target that should bind yourself, to others. They are not part of the Contract.
Explicitly you can not use a Wyrd Dream to do this. I had thought this might be a possibility but it is not.
Only Contracts that can be used on targets other than the Contract’s user may be invested into a Wyrd-dream: thus, Contracts that permit shapechanging and other effects used only by the wielder cannot be granted to others.
If you wanted to create one, I suggest:
6th dot of Fang and Talon. Adding a Secret, customised 6th dot contract is something I and a few other GMs have played around with. It indicated a truly powerful character, with capacities few others can imagine. To have a 6th dot contract you would need at least Wyrd 6. It would not be a mere matter of learning it (signing into effect a clause on a contract you were always part of), but a matter of forging a new clause (and how that was done would be a story in and of itself).
5 dot Goblin Contract or 5 dot Token, with quite a downside. If it is not meant to be a big deal, the Goblin Market is a source for all kinds of things that are not normally allowed by the rules. But they come with big drawbacks.
Lord Sage of Unknown Reaches with a Imbued Item.
The final option is quiet convoluted. But potentially viable. By RAW it is 100% legal. (Leaving aside by RAI, you should be very careful about mixing other Supernatural Splats into your games) I would be very cautious allowing it in my game, unless my chronicle was focuses around the Freehold interacting with the concilium of mages.
The Lord Sages of the Unknown Reaches (Page 147 of Rite of Spring) are an entitlement about dealing with other Supernaturals. They are one of the most powerful entitlements in the game (by powerful I mean most flexible). One of the benefits of joining them is the ability to take the merit "Imbued Item" from Mage the Awakening. The Lord Sages of the Unknown Reaches are surprisingly easy to get into. Requires Wyrd 2 and Occult 3 with 2 specialities.
A Imbued Item from Mage the Awakening (page 84 of the Mage rulebook), Can do this. Imbued Items are (again by RAW) not restricted to the 5 dot maximum. Notice that almost all other merits are labelled like "•• to •••••". This point could be contested. By RAW getting Clarity above 5 only removes the restriction on dots of attribute, skill and contracts. However also by RAW, there is no restriction ever placed on the number of merit dots (check chapter 5 nwod core)
Imbued items have a base merit cost of:
- 1 dot base
- +1 dot to give it a mana pool
Then it needs the spell. There are 2 suitable spells in Mage:
- +4 Dots to give it the Life •••• Shapechanging spell, which lets the user transform (Page 190 of Mage). This has the risk of losing your mind to the animal instincts. It is Target self so the Lord Sage would have to give it to the the target and get them to activate it.
- +5 Dots Greater Shapechanging (page page 192). As above but without the risk of losing self. Also unlike base Shapechanging, it can target others.
If you want it to be usable without having to go to a Mage to recharge its Mana Pool, then it will need a spell to harvest Mana added. Theoretically this could be a separate item, and the mana could be stored in the changeling - +1 dot to add a second spell - There are a variety of Prime spells at Prime 4 (thus not increasing the cost of the item), that will harvest mana. - The most mechanically advantageous is Siphon Integrity (on Page 229) - Logically, as Siphon Essence is a 4 dot prime, a improvised Convert Glamour would also be 4 dot prime, and would allow a changeling to power the item with Glamour. - It would also be able to have a siphon glamour by the same logic, allowing the changeling to force the Target to to pay the cost in glamour.
As I said, I don't recommend this. But once I got thinking about it, I couldn't get it out of my head, and had to work out if it was possible. I have come to the conclusion it is legal.
As GM I would be extremely cautious about bringing such an item into the game. As a player I would never suggest that the GM lets me start with it, or acquire it somehow.
I have split this into a separate answer, because it is long, convoluted and is a very separate solution. See my original answer for something more Changeling